Reintroductions are commonly employed to preserve intraspecific biodiversity in
fragmented landscapes. However, reintroduced populations are frequently smaller and
more geographically isolated than native populations. Mixing genetically, divergent
sources are often proposed to attenuate potentially low genetic diversity in reintroduced
populations that may result from small effective population sizes. However, a possible
negative tradeoff for mixing sources is outbreeding depression in hybrid offspring. We
examined the consequences of mixed-source reintroductions on several fitness surrogates
at nine slimy sculpin (Cottus cognatus) reintroduction sites in south-east Minnesota. We
inferred the relative fitness of each crosstype in the reintroduced populations by
comparing their growth rate, length, weight, body condition and persistence in
reintroduced populations. Pure strain descendents from a single source population
persisted in a greater proportion than expected in the reintroduced populations, whereas
all other crosstypes occurred in a lesser proportion. Length, weight and growth rate were
lower for second-generation intra-population hybrid descendents than for pure strain
and first-generation hybrids. In the predominant pure strain, young-of the-year size was
significantly greater than any other crosstype. Our results suggested that differences in
fitness surrogates among crosstypes were consistent with disrupted co-adapted gene
complexes associated with beneficial adaptations in these reintroduced populations.
Future reintroductions may be improved by evaluating the potential for local adaptation
in source populations or by avoiding the use of mixed sources by default when
information on local adaptations or other genetic characteristics is lacking.
Huff, David, D.; Miller, Loren, M.; Chizinski, Christopher, J.; Vondracek, Bruce.
Mixed-source reintroductions lead to outbreeding depression in second-generation descendents of a native North American fish.
Retrieved from the University of Minnesota Digital Conservancy,
Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.